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Chapter 16 — STRUCTURAL DESIGN

Section 1613 — EARTHQUAKE LOADS

2025 California Building Code (Title 24, Part 2) · 2025 edition · updated 2026-07-29 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

1613.1 Scope.

Every structure, and portion thereof, including nonstructural components that are permanently attached to structures and their supports and attachments, shall be designed and constructed to resist the effects of earthquake motions in accordance with Chapters 11, 12, 13, 15, 17 and 18 of ASCE 7, as applicable. The seismic design category for a structure is permitted to be determined in accordance with Section 1613 or ASCE 7.

Exceptions:

  1. Detached one- and two-family dwellings, assigned to Seismic Design Category A, B or C.
  2. The seismic force-resisting system of wood-frame buildings that conform to the provisions of Section 2308 are not required to be analyzed as specified in this section. [OSHPD 1R, 2 & 5] Not permitted by OSHPD, see Section 2308.
  3. Agricultural storage structures intended only for incidental human occupancy.
  4. Structures that require special consideration of their response characteristics and environment that are not addressed by this code or ASCE 7 and for which other regulations provide seismic criteria, such as vehicular bridges, electrical transmission towers, hydraulic structures, buried utility lines and their appurtenances and nuclear reactors.
  5. References within ASCE 7 to Chapter 14 shall not apply, except as specifically required herein.
  6. Temporary structures complying with Section 3103.6.1.4.

1613.1.1 Scope. [SL] For applications listed in Section 1.12 regulated by the State Librarian, only the provisions of ASCE 7 Tables 13.5- 1 and 1607.1, as amended, of this code shall apply.

1613.1.2 State-owned buildings. [BSC] State-owned buildings, including those of the University of California, CSU and Judicial Council, shall not be constructed where any portion of the foundation would be within a mapped area of earthquake-induced lique- faction or landsliding or within 50 feet of a mapped fault rupture hazard as established by Section 1803.7.

1613.1.3 Existing state buildings. [BSC] Additions, alterations, repairs or change of occupancy category of existing buildings shall be in accordance with the California Existing Building Code, Part 10.

1613.2 Determination of seismic design category.

Structures shall be assigned to a seismic design category based on one of the following methods unless the authority having jurisdiction or geotechnical data determines that Site Class DE, E or F soils are present at the site:

  1. Based on the structure risk category using Figure 1613.2(1).

  2. Determined in accordance with ASCE 7.

Where Site Class DE, E or F soils are present, the seismic design category shall be determined in accordance with ASCE 7.

[OSHPD 1R, 2 & 5] Seismic design category shall be D or higher.

16-34 2025 CALIFORNIA BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

STRUCTURAL DESIGN

FIGURE 1613.2(1)—SEISMIC DESIGN CATEGORIES FOR DEFAULT SITE CONDITIONS FOR THE CONTERMINOUS UNITED STATES (WESTERN)

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

STRUCTURAL DESIGN

1613.3 Simplified design procedure.

Where the alternate simplified design procedure of ASCE 7 is used, the seismic design category shall be determined in accordance with ASCE 7.

1613.4 Ballasted photovoltaic panel systems.

Ballasted, roof-mounted photovoltaic panel systems need not be rigidly attached to the roof or supporting structure. Ballasted, unattached PV panel systems shall be designed and installed only on roofs with slopes not more than 1 unit vertical in 12 units horizontal. Ballasted, unattached PV panel systems shall be designed to accommodate sliding in accordance with ASCE 7 Chapter 13. [OSHPD 1R, 2 & 5] Ballasted photovoltaic panel systems shall be considered as an alternative system.

1613.5 Elevators, escalators and other conveying systems.

Elevators, escalators and other conveying systems and their components shall satisfy the seismic requirements of ASCE 7 and ASME A17.1/CSA B44 as applicable.

1613.6 Automatic sprinkler systems.

Where required, automatic sprinkler systems, including anchorage and bracing, shall comply with ASCE 7 and Section 903.3.1.1.

1613.7 Component importance factors.

1613.7 Component importance factors. [OSHPD 1R, 2 & 5] Nonstructural components designated below shall have a component importance factor, I p , equal to 1.5: 1. For components that are required for life-safety purposes after an earthquake, including emergency and standby power systems, mechanical smoke removal systems, fire protection sprinkler systems and fire alarm control panels. 2. For medical equipment required for patient life support.

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▸ Contents — 2025 California Building Code (Title 24, Part 2)
2025 California Building Code (Title 24, Part 2)
  1. Chapter 1 — ADMINISTRATION
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — OCCUPANCY CLASSIFICATION AND USE
  4. Chapter 4 — SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY A…
  5. Chapter 5 — GENERAL BUILDING HEIGHTS AND AREAS
  6. Chapter 6 — TYPES OF CONSTRUCTION
  7. Chapter 7 — FIRE AND SMOKE PROTECTION FEATURES
  8. Chapter 7A — MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR W…
  9. Chapter 8 — INTERIOR FINISHES
  10. Chapter 9 — FIRE PROTECTION AND LIFE SAFETY SYSTEMS
  11. Chapter 10 — MEANS OF EGRESS
  12. Chapter 11 — RESERVED
  13. Chapter 11A — HOUSING ACCESSIBILITY
  14. Chapter 11B — ACCESSIBILITY TO PUBLIC BUILDINGS, PUBLIC ACCOMM…
  15. Chapter 12 — INTERIOR ENVIRONMENT
  16. Chapter 13 — ENERGY EFFICIENCY
  17. Chapter 14 — EXTERIOR WALLS
  18. Chapter 15 — ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
  19. ▸ Chapter 16 — STRUCTURAL DESIGN
    Overview
    1. Section 1601 — GENERAL
    2. Section 1602 — NOTATIONS
    3. Section 1603 — CONSTRUCTION DOCUMENTS
    4. Section 1604 — GENERAL DESIGN REQUIREMENTS
    5. Section 1605 — LOAD COMBINATIONS
    6. Section 1606 — DEAD LOADS
    7. Section 1607 — LIVE LOADS
    8. Section 1608 — SNOW LOADS
    9. Section 1609 — WIND LOADS
    10. Section 1610 — SOIL LOADS AND HYDROSTATIC PRESSURE
    11. Section 1611 — RAIN LOADS
    12. Section 1612 — FLOOD LOADS
    13. Section 1613 — EARTHQUAKE LOADS
    14. Section 1614 — ATMOSPHERIC ICE LOADS
    15. Section 1615 — TSUNAMI LOADS
    16. Section 1616 — STRUCTURAL INTEGRITY
    17. Section 1617 — ADDITIONAL REQUIREMENTS FOR COMMUNITY COLLEGES …
  20. Chapter 16A — STRUCTURAL DESIGN
  21. Chapter 17 — SPECIAL INSPECTIONS AND TESTS
  22. Chapter 17A — SPECIAL INSPECTIONS AND TESTS
  23. Chapter 18 — SOILS AND FOUNDATIONS
  24. Chapter 18A — SOILS AND FOUNDATIONS
  25. Chapter 19 — CONCRETE
  26. Chapter 19A — CONCRETE
  27. Chapter 20 — ALUMINUM
  28. Chapter 21 — MASONRY
  29. Chapter 21A — MASONRY
  30. Chapter 22 — STEEL
  31. Chapter 22A — STEEL
  32. Chapter 23 — WOOD
  33. Chapter 24 — GLASS AND GLAZING
  34. Chapter 25 — GYPSUM PANEL PRODUCTS AND PLASTER
  35. Chapter 26 — PLASTIC
  36. Chapter 27 — ELECTRICAL
  37. Chapter 28 — MECHANICAL SYSTEMS
  38. Chapter 29 — PLUMBING SYSTEMS
  39. Chapter 30 — ELEVATORS AND CONVEYING SYSTEMS
  40. Chapter 31 — SPECIAL CONSTRUCTION
  41. Chapter 31A — SYSTEMS FOR WINDOW CLEANING OR EXTERIOR BUILDING…
  42. Chapter 31B — PUBLIC POOLS
  43. Chapter 31C — RADIATION
  44. Chapter 31D — FOOD ESTABLISHMENTS
  45. Chapter 31F — MARINE OIL TERMINALS
  46. Chapter 32 — ENCROACHMENTS INTO THE PUBLIC RIGHT-OF-WAY
  47. Chapter 33 — SAFEGUARDS DURING CONSTRUCTION
  48. Chapter 34 — RESERVED
  49. Chapter 35 — REFERENCED STANDARDS
  50. Appendix A — EMPLOYEE QUALIFICATIONS
  51. Appendix B — BOARD OF APPEALS
  52. Appendix C — GROUP U—AGRICULTURAL BUILDINGS
  53. Appendix D — FIRE DISTRICTS
  54. Appendix E — RESERVED
  55. Appendix F — RODENTPROOFING
  56. Appendix G — FLOOD-RESISTANT CONSTRUCTION
  57. Appendix H — SIGNS
  58. Appendix I — PATIO COVERS
  59. Appendix J — GRADING
  60. Appendix K — GROUP R-3 AND GROUP R-3.1 OCCUPANCIES PROTECTED B…
  61. Appendix L — EARTHQUAKE RECORDING INSTRUMENTATION
  62. Appendix M — TSUNAMI-GENERATED FLOOD HAZARDS
  63. Appendix N — REPLICABLE BUILDINGS
  64. Appendix O — PERFORMANCE-BASED APPLICATION
  65. Appendix P — SLEEPING LOFTS
  66. Appendix Q — EMERGENCY HOUSING

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